Biology; The Living Science. Prentice Hall, 1998, Miller, Kenneth R and Levine, Joseph.
Subject: Biology
Grade: 10th
Age: 15-16
Target ability levels:?
Chapter title: DNA and RNA
PART 2: UNPACKING A LEARNING GOAL
R.I K-12 Grade Span Expectations in Science. Life Science LS-1 (9-11)-2 Students demonstrate an understanding of the molecular basis for heredity by... 2c describing how DNA contains the code for the production of specific proteins.
1) What does the standard mean?
Cells store and use information to guide their functions. The genetic information stored in DNA is used to direct the synthesis of the thousands of proteins that each cell requires.
In all organisms, the instructions for specifying the characteristics of the organism are carried in DNA, a large polymer formed from subunits of four kinds (A,G,C,and T). The chemical and structural properties of DNA explain how the genetic information that underlies heredity is both encoded in genes (as a string of molecular "letters") and replicated (by a templating mechanism). Each DNA molecule in a cell forms a single chromosome.
2) What prior knowledge do students need to understand the standard?
• need to understand cell division and know about the cell cycle
• need to be familiar with the concept of genetics: genes, chromosomes, mitosis, meiosis
• need to be familiar with the concept of inheritance and Mendel's principles of genetics (ex: many human traits are inherited by the action of genes that have dominant and recessive alleles).
3) What misconceptions might students hold about the topic?
• students don't understand how a genetic change can result in a phenotypic change at the protein level
• students rarely understand the importance and prevalence of proteins in cells; don't understand that proteins "get made" from DNA
• don't understand the relationship between DNA, genes, and chromosomes
PART 3: ANALYZING THE SELECTED FEATURES OF THE TEXTBOOK
Category III: Engaging Students with Relevant Phenomena
Criterion III.A: Providing a Variety of Phenomena
The topic of DNA and RNA is covered throughout the chapter. However, the textbook does not provide multiple and varied phenomena to support the key ideas. It does provide some phenomena that could be used to support the key ideas; it’s just not very substantial. Also, it only provides some phenomena that are explicitly linked to the relevant key ideas.
Sightings that pertain to the criterion:
Genes are made of DNA. This is based on Avery’s study of the process of transformation and on the experiment by Hershey and Chase, which was about the radioactive isotopes in bacteriophages (pg. 173)
DNA is a nucleic acid, one of the four macromolecules (pg.175)
Figure 8-7 shows DNA double helix and its structure
Figure 8-8 shows DNA replication, where each strand serves as a pattern for the synthesis of a complementary strand. The result is two double-stranded DNA molecules, each an exact copy of the original molecule.
Genetic info is contained in chromosomes which are located in the nucleus (pg.179)
Chromosomes are made of chromatin which consists of DNA and proteins
RNA is the principal molecule that carries out the instructions coded in the DNA (pg.181)
Definition of transcription is provided on pg. 182
Explanation of three kinds of RNA is described on pg. 182-183
Translation is explained on pg 184
A section of DNA – a gene – directs the synthesis of a protein (pg 186)
Although these above listed phenomena are represented in the text, they are not very comprehensive. However, the chapter does provide some phenomena that meet indicators 1 and 2 on the Project 2061 criteria.
Indicators of meeting this criterion according to the PROJECT 2061
Phenomena could be used to support the key ideas.
Phenomena are explicitly linked to the relevant key ideas
Therefore, based on these indicators and the rating scheme, the rating for this criterion is Satisfactory.
Criterion III.B: Providing Vivid Experiences
The chapter does not include many activities that provide firsthand experiences with the phenomena. However, on pg.185 is an illustration of Visualizing Protein Synthesis and it does serve as a good visual to comprehend the concept. Also, there is a laboratory investigation on Extracting DNA which provides the students with a vicarious experience. They will be able to observe DNA after they extract it from wheat germ.
Indicators of meeting this criterion according to the PROJECT 2061
Each firsthand experience is efficient (when compared to other firsthand experiences) and, if several firsthand experiences target the same idea, the set of firsthand experiences is efficient. (The efficiency of an experience equals the cost of the experience [in time and money] in relation to its value.)
The experiences that are not firsthand (e.g., text, pictures, video) provide students with a vicarious sense of the phenomena. (Please note that if the material provides only firsthand experiences, this indicator is not applicable.)
The set of firsthand and vicarious experiences is sufficient.
Therefore, based on these indicators and the rating scheme, the rating for this criterion is Satisfactory.
Category IV: Developing and Using Scientific Ideas
· Criterion IV.B: Representing Ideas Effectively
All those sightings of phenomena that I listed on top of criterion III.A appear to be represented accurately. However, there are a few sections in the textbook that represent the material in a very superficial way and don’t seem to make comprehensible representations of the key ideas. Also, there is one section of the chapter that doesn’t represent the process of transcription accurately.
For example:
When explaining DNA replication, the chapter only briefly mentions the cell cycle. On pg. 179, it says “DNA replication takes place during the synthesis phase (S-phase) of the cell cycle”. It would have been clearer to understand if this section would have been accompanied by an illustration of the full cell cycle.
When explaining the process of transcription, the chapter inaccurately states on pg.182 that DNA gets directly transcribed into messenger RNA (mRNA) and then into proteins. Actually, DNA does not get transcribed directly into mRNA. First it has to be transcribed into pre-messenger RNA (pre-mRNA) and only then can it be transcribed into mRNA and followed by a translation into proteins. I think it’s very important for the students to understand that pre-mRNA is involved because the DNA strand has to be first copied into the pre-mRNA and then into the mRNA. It’s not possible to go directly from DNA to mRNA. There has to be the intermediary pre-m RNA to make this process successful.
The chapter does not mention the fact that mRNA is being translated into proteins in the cytoplasm. It simply mentions that it will be translated but it doesn’t provide the location. This is not a comprehensible representation of key ideas.
Indicators of meeting this criterion according to the PROJECT 2061
Representation is accurate (or, if not accurate, then students are asked to critique the representation).
Representation is likely to be comprehensible to students.
Representation is explicitly linked to the real thing.
Therefore, based on these indicators and the rating scheme, the rating for this criterion is Satisfactory.
PART 4: APPLYING MY EVALUATION TO THINK ABOUT MY TEACHING**
· Phenomena, representations, and experiences that I think should be included in one lesson addressing this topic:
To start, it would be important to clearly define what DNA is and where it’s located in the cells (inside the nucleus), then it would be important to describe what RNA is and where the proteins get translated (in the cytoplasm). I believe that a very valuable visual representation would be to draw a diagram on the board which would show the flow of the three main processes: DNA-RNA-PROTEINS. By providing this sequential main key idea, I could then individually address each specific step and all the details of it.
Also, I would provide a representation of a cell which would clearly show the location of the nucleus (home of DNA) and the location of the cytoplasm (home of protein factories). By referring to the visual representation, I would explain the process of transcription (from DNA to pre-mRNA to mRNA) and translation (from mRNA to proteins).
As an extra reinforcement, I would show a short video animation of DNA transcription and RNA translation. This will be valuable especially for visual and auditory learners in the classroom but the whole class would benefit from it.
Time permitting, I would form small study groups and provide each group with a long set of letters (A-s, T-s, G-s, and C-s, which will represent the nucleotides). I then would assign each group to first transcribe the letters and then translate them into amino acids (from which proteins can be translated). For this section of the activity, I would also provide them with a list of names of amino acids. They would be able to match their translated letters with the names of the amino acids. This activity would provide them an inquiry based learning experience directly related to the key ideas of the topic.
How will I have the students use their text in conjunction with my lesson to understand the topic of DNA and RNA
I would still assign them to read the chapter on DNA and RNA. I would also invite them to study the illustrations and complete the end of the chapter review and chapter questions. However, I would supplement the parts of the book, where information is not comprehensible or where it’s not accurately represented. For example, I would clearly explain to them that DNA must be transcribed into pre-mRNA prior to mRNA. I would also supplement the chapter by clearly defining the location for each process. That is, transcription takes place in the nucleus and translation in the cytoplasm. Lastly, we would still perform the laboratory investigation Extracting DNA, represented in the book.
Biology; The Living Science. Prentice Hall, 1998, Miller, Kenneth R and Levine, Joseph.
Subject: Biology
Grade: 10th
Age: 15-16
Target ability levels:?
Chapter title: DNA and RNA
PART 2: UNPACKING A LEARNING GOAL
R.I K-12 Grade Span Expectations in Science. Life Science
LS-1 (9-11)-2 Students demonstrate an understanding of the molecular basis for heredity by...
2c describing how DNA contains the code for the production of specific proteins.
1) What does the standard mean?
Cells store and use information to guide their functions. The genetic information stored in DNA is used to direct the synthesis of the thousands of proteins that each cell requires.
In all organisms, the instructions for specifying the characteristics of the organism are carried in DNA, a large polymer formed from subunits of four kinds (A,G,C,and T). The chemical and structural properties of DNA explain how the genetic information that underlies heredity is both encoded in genes (as a string of molecular "letters") and replicated (by a templating mechanism). Each DNA molecule in a cell forms a single chromosome.
2) What prior knowledge do students need to understand the standard?
• need to understand cell division and know about the cell cycle
• need to be familiar with the concept of genetics: genes, chromosomes, mitosis, meiosis
• need to be familiar with the concept of inheritance and Mendel's principles of genetics (ex: many human traits are inherited by the action of genes that have dominant and recessive alleles).
3) What misconceptions might students hold about the topic?
• students don't understand how a genetic change can result in a phenotypic change at the protein level
• students rarely understand the importance and prevalence of proteins in cells; don't understand that proteins "get made" from DNA
• don't understand the relationship between DNA, genes, and chromosomes
PART 3: ANALYZING THE SELECTED FEATURES OF THE TEXTBOOK
Category III: Engaging Students with Relevant Phenomena
The topic of DNA and RNA is covered throughout the chapter. However, the textbook does not provide multiple and varied phenomena to support the key ideas. It does provide some phenomena that could be used to support the key ideas; it’s just not very substantial. Also, it only provides some phenomena that are explicitly linked to the relevant key ideas.
Sightings that pertain to the criterion:
Although these above listed phenomena are represented in the text, they are not very comprehensive. However, the chapter does provide some phenomena that meet indicators 1 and 2 on the Project 2061 criteria.
Indicators of meeting this criterion according to the PROJECT 2061
- Phenomena could be used to support the key ideas.
- Phenomena are explicitly linked to the relevant key ideas
Therefore, based on these indicators and the rating scheme, the rating for this criterion is Satisfactory.The chapter does not include many activities that provide firsthand experiences with the phenomena. However, on pg.185 is an illustration of Visualizing Protein Synthesis and it does serve as a good visual to comprehend the concept. Also, there is a laboratory investigation on Extracting DNA which provides the students with a vicarious experience. They will be able to observe DNA after they extract it from wheat germ.
Indicators of meeting this criterion according to the PROJECT 2061
- Each firsthand experience is efficient (when compared to other firsthand experiences) and, if several firsthand experiences target the same idea, the set of firsthand experiences is efficient. (The efficiency of an experience equals the cost of the experience [in time and money] in relation to its value.)
- The experiences that are not firsthand (e.g., text, pictures, video) provide students with a vicarious sense of the phenomena. (Please note that if the material provides only firsthand experiences, this indicator is not applicable.)
- The set of firsthand and vicarious experiences is sufficient.
Therefore, based on these indicators and the rating scheme, the rating for this criterion is Satisfactory.Category IV: Developing and Using Scientific Ideas
· Criterion IV.B: Representing Ideas Effectively
All those sightings of phenomena that I listed on top of criterion III.A appear to be represented accurately. However, there are a few sections in the textbook that represent the material in a very superficial way and don’t seem to make comprehensible representations of the key ideas. Also, there is one section of the chapter that doesn’t represent the process of transcription accurately.
For example:
Indicators of meeting this criterion according to the PROJECT 2061
- Representation is accurate (or, if not accurate, then students are asked to critique the representation).
- Representation is likely to be comprehensible to students.
- Representation is explicitly linked to the real thing.
Therefore, based on these indicators and the rating scheme, the rating for this criterion is Satisfactory.PART 4: APPLYING MY EVALUATION TO THINK ABOUT MY TEACHING**
· Phenomena, representations, and experiences that I think should be included in one lesson addressing this topic:
To start, it would be important to clearly define what DNA is and where it’s located in the cells (inside the nucleus), then it would be important to describe what RNA is and where the proteins get translated (in the cytoplasm). I believe that a very valuable visual representation would be to draw a diagram on the board which would show the flow of the three main processes: DNA-RNA-PROTEINS. By providing this sequential main key idea, I could then individually address each specific step and all the details of it.
Also, I would provide a representation of a cell which would clearly show the location of the nucleus (home of DNA) and the location of the cytoplasm (home of protein factories). By referring to the visual representation, I would explain the process of transcription (from DNA to pre-mRNA to mRNA) and translation (from mRNA to proteins).
As an extra reinforcement, I would show a short video animation of DNA transcription and RNA translation. This will be valuable especially for visual and auditory learners in the classroom but the whole class would benefit from it.
Time permitting, I would form small study groups and provide each group with a long set of letters (A-s, T-s, G-s, and C-s, which will represent the nucleotides). I then would assign each group to first transcribe the letters and then translate them into amino acids (from which proteins can be translated). For this section of the activity, I would also provide them with a list of names of amino acids. They would be able to match their translated letters with the names of the amino acids. This activity would provide them an inquiry based learning experience directly related to the key ideas of the topic.
- How will I have the students use their text in conjunction with my lesson to understand the topic of DNA and RNA
I would still assign them to read the chapter on DNA and RNA. I would also invite them to study the illustrations and complete the end of the chapter review and chapter questions. However, I would supplement the parts of the book, where information is not comprehensible or where it’s not accurately represented. For example, I would clearly explain to them that DNA must be transcribed into pre-mRNA prior to mRNA. I would also supplement the chapter by clearly defining the location for each process. That is, transcription takes place in the nucleus and translation in the cytoplasm. Lastly, we would still perform the laboratory investigation Extracting DNA, represented in the book.